[browser] Allow `WasmDebugLevel=0` for debug builds

[maraf]

• Currently we force non-zero debug level for debug builds
• We override the value even when user explicitly specify 0
• Beside other effects, it forces runtime to download pdbs and there is not direct way for user to bypass it

runtime/src/mono/wasm/build/WasmApp.targets

Line 146 in 3295789

<WasmDebugLevel Condition="('$(WasmDebugLevel)' == '' or '$(WasmDebugLevel)' == '0') and ('$(DebuggerSupport)' == 'true' or '$(Configuration)' == 'Debug')">-1</WasmDebugLevel>

runtime/src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets

Line 208 in 3295789

<_WasmDebugLevel Condition="'$(_WasmDebugLevel)' == '0' and ('$(DebuggerSupport)' == 'true' or '$(Configuration)' == 'Debug')">-1</_WasmDebugLevel>

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Issue Details

---

• Currently we force non-zero debug level for debug builds
• We override the value even when user explicitly specify 0
• Beside other effects, it forces runtime to download pdbs and there is not direct way for user to bypass it

runtime/src/mono/wasm/build/WasmApp.targets

Line 146 in 3295789

<WasmDebugLevel Condition="('$(WasmDebugLevel)' == '' or '$(WasmDebugLevel)' == '0') and ('$(DebuggerSupport)' == 'true' or '$(Configuration)' == 'Debug')">-1</WasmDebugLevel>

runtime/src/mono/nuget/Microsoft.NET.Sdk.WebAssembly.Pack/build/Microsoft.NET.Sdk.WebAssembly.Browser.targets

Line 208 in 3295789

<_WasmDebugLevel Condition="'$(_WasmDebugLevel)' == '0' and ('$(DebuggerSupport)' == 'true' or '$(Configuration)' == 'Debug')">-1</_WasmDebugLevel>

Author:	maraf
Assignees:	maraf
Labels:	arch-wasm, area-Build-mono, os-browser
Milestone:	9.0.0

[maraf]

@radical Do we remember why we enforced non-zero debug level for debug builds?

[radical]

@radical Do we remember why we enforced non-zero debug level for debug builds?

To allow debugging, and get the debug messages from the runtime, I assume. cc @thaystg
Not downloading pdb files sounds like a very niche case, and if we want to support that then it should be by some other mechanism. We should not change the default because of that.

[thaystg]

We force -1 to allow debugging and do NOT get debug messages from the runtime.
To get debug messages from the runtime we need to pass numbers >= 1.

[maraf]

Is it the correct behavior if user explicitly want it turned off (by setting WasmDebugLevel=0 in csproj/cmd)? I would expect it to be a default behavior when WasmDebugLevel is empty. Also, the override doesn't in WasAppBuilder when the property is set on cmd line.

[radical]

Is it the correct behavior if user explicitly want it turned off (by setting WasmDebugLevel=0 in csproj/cmd)?

Hm that does sound a bit wrong. I think we might have had WasmDebugLevel=0 being set by default elsewhere, and this was reacting to it. Try changing the condition to <WasmDebugLevel Condition="'$(WasmDebugLevel)' == '' and ('$(DebuggerSupport)' == 'true' or '$(Configuration)' == 'Debug')">-1</WasmDebugLevel> and see how WBT fares. And try debugging blazor, and wasm template apps.

[radical]

Also, see

runtime/eng/testing/tests.browser.targets

Lines 179 to 188 in c9a985d

	<!--
	Do this *after* importing WasmApp.targets. tests.wasm.targets sets this to `reset-to-zero` to indicate
	that we want to force this value to zero.
	WasmApp.targets *overrides* `WasmDebugLevel` when `DebuggerSupport=true`, but for the library tests
	we explicitly want to:
	1. build with DebuggerSupport=true so the debugger attributes are preserved by the linker;
	2. *debugging* is disabled at run time so the interpreter optimizations don't get disabled.
	-->
	<WasmDebugLevel Condition="'$(WasmDebugLevel)' == 'reset-to-zero'">0</WasmDebugLevel>

. And check debugging library tests also, though I haven't tried it in quite some time, but the wasmapphost PR had it working.